1. Field of the Invention
The present invention relates to fluorescent light fixtures and, more particularly, to fixtures having a removable ballast.
2. Description of the Prior Art
Replacement of the heavy ballast used in fluorescent light fixtures is a difficult and time consuming task. Usually the entire fixture has to be dismantled and numerous wires disconnected before a ballast can be removed. During replacement, great care is always necessary to insure the correct wires are reattached to the proper leads on the new ballast.
Attempts to overcome the above disadvantages are described in U.S. Pat. Nos. 2,702,378 and 3,040,170. In the U.S. Pat. No. 2,702,378 patent, electrical contact fingers extend from the ballast ends and are retained within corresponding sockets of connector blocks mounted in the fixture housing. Ballast replacement occurs by lifting the old ballast out of the area between the blocks and putting a new one in its place. The ballast includes an integral flat plate which suspends the ballast over the housing opening.
From the above, it would seem that little was gained in the way of economy or convenience. Specially made connector blocks with sockets are required and, in addition to predetermined opposing fingers, each ballast must include a large integral plate across the top. Access to the fixture top is not always easy and side entry requires removal of the connector blocks and their adaptation to the integral plate.
The U.S. Pat. No. 3,040,170 patent discloses an external ballast having terminals insertable into fixture casing sockets. The ballast includes a slotted end flange so that a sheet metal screw may secure the ballast to the fixture.
While the above is an improvement, it is useless for light fixtures mounted flush to the ceiling. Note the ballast simply rests upon the top of the fixture casing and is held against forces by the metal screw and terminal connectors. Also, a problem with both of the above patents is the relative fragility of the outwardly extending electrical fingers. It will be appreciated that ballast is very heavy and the thin male connectors are especially vulnerable to bending or breakage.